نتایج جستجو برای: expanded porphyrins
تعداد نتایج: 64232 فیلتر نتایج به سال:
Porphyrins are known to be efficient photosensitizer molecules and the combined action of light and porphyrins in Propionibacterium acnes have a lethal action on the cells. Identification and quantification of in situ porphyrins in P. acnes have been done using an integrating sphere connected to an ordinary absorption spectrophotometer, and the amounts of porphyrins in the cells were quantified...
Functionalized asymmetric porphyrins bearing highly reactive centers in substituents at the mesopositions were synthesized in good yields by the reaction of 5,15-diphenylporphyrin with organolithium reagents. Using these porphyrins as precursors highly complex tetrapyrrolic systems are accessible. The synthetic strategy is based on our earlier reports on the combined use of organolithium and al...
Methods developed for porphyrin analysis have low recoveries and/or poor precision for the less polar protoporphyrin IX. We describe a simple method of analysis of porphyrins and biliverdin in bile and excreta of birds based on extraction with HCl 3N: acetonitrile and HPLC/UV analyses. Recoveries were good for protoporphyrin IX and other porphyrins (>79%). Applications of this method showed tha...
Porphyrias are a family of inherited diseases, each associated with a partial defect in one of the enzymes of the heme biosynthetic pathway. In six of the eight porphyrias described, the main clinical manifestation is skin photosensitivity brought about by the action of light on porphyrins, which are deposited in the upper epidermal layer of the skin. Porphyrins absorb light energy intensively ...
The inhibition of the corrosion of N80 steel in 3.5 wt. % NaCl solution saturated with CO2 by four porphyrins, namely 5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphyrin (HPTB), 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphyrin (T4PP), 4,4',4″,4‴-(porphyrin-5,10,15,20-tetrayl)tetrakis(benzoic acid) (THP) and 5,10,15,20-tetraphenyl-21H,23H-porphyrin (TPP) was studied using electrochemical impedan...
The synthesis and characterization of new meso-substituted and -substituted unsymmetrical metallorphyrins has been described. A new modified Alder method was used for the synthesis of unsymmetrical porphyrins. Reaction of these unsymmetrical porphyrins with metal chlorides and nitrates afforded the corresponding metalloporphyrins in high yields with excellent purity. These porphyrins and their...
Charge-transfer (CT) π-complexes are formed between planar porphyrins and 1,4,5,8,9,12-hexaazatriphenylene (HAT) derivatives with large formation constants (e.g., 104 M-1), exhibiting broad CT absorption bands. The unusually large formation constants result from close face-to-face contact between two planar π-planes of porphyrins and HAT derivatives. The redox potentials of porphyrins and HAT d...
A procedure has been developed for the assay of urinary porphyrins. Total porphyrins are extracted from acidified urine into n-butanol. The fluorescence of this solution under ultraviolet illumination gives a preliminary indication of abnormal levels of porphyrins. They are then separated and identified by thin-layer chromatography. Uroporphyrin and coproporphyrin can be qualitatively estimated...
The synthesis and photophysical properties of cyano and ethynyl substituted carbazole-based porphyrins were investigated. The introduction of ethynyl groups induced red shifts, while that of cyano groups induced blue shifts of their absorption bands, which was supported by MO calculations. Ethylenedioxy-appended porphyrins were also prepared via a coupling reaction. The conjugated and electroni...
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